Starch-loaded polyvinyl alcohol copolymer film for packaging non-liquid product and method for making the same

ABSTRACT

A water-soluble film for packaging a non-liquid product, a package employing the film, and methods of making the same, are disclosed. The film is made from a hydrolyzed copolymer of vinyl acetate and methyl acrylate in a range of from about 30 to about 95 percent by weight, modified starch in a range of from about 4 to about 30 percent by weight, plasticizer in a range of from about 5 to about 30 percent by weight, lubricant/release agent in a range of from about 0.0 to about 1.5 percent by weight, and surfactant in a range of from about 0.01 to about 1.5 percent by weight.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This is a continuation-in-part of U.S. patent application Ser.No. 10/367,050, filed Feb. 14, 2003.

TECHNICAL FIELD

[0002] The present invention relates generally to water-solublepolyvinyl alcohol (PVOH) film. More specifically, the present inventionrelates to water-soluble PVOH film with particular applications forpackaging of non-liquid products, such as cleansers, conditioners,disinfectants, and the like.

BACKGROUND

[0003] Polyvinyl alcohol (PVOH) is a synthetic resin generally preparedby the alcoholysis, usually termed hydrolysis or saponification, ofpolyvinyl acetate. Fully hydrolyzed PVOH, where virtually all theacetate groups have been converted to alcohol groups, is a stronglyhydrogen-bonded, highly crystalline polymer which dissolves only in hotwater—greater than about 140° F. (60° C.). If a sufficient number ofacetate groups are allowed to remain after the hydrolysis of polyvinylacetate, the PVOH polymer then being known as partially hydrolyzed, itis more weakly hydrogen-bonded and less crystalline and is soluble incold water—less than about 50° F. (10° C.). Both fully and partiallyhydrolyzed PVOH types are commonly referred to as PVOH homopolymersalthough the partially hydrolyzed type is technically a vinylalcohol-vinyl acetate copolymer.

[0004] The term PVOH copolymer is generally used to describe polymersthat are derived by the hydrolysis of a copolymer of a vinyl ester,typically vinyl acetate, and another monomer. PVOH copolymers can betailored to desired film characteristics by varying the kind andquantity of copolymerized monomers. Examples of copolymerizations arethose of vinyl acetate with a carboxylic acid or with an ester of acarboxylic acid. Again, if the hydrolysis of acetate groups in thesecopolymers is only partial, then the resulting polymer could bedescribed as a PVOH terpolymer—having vinyl acetate, vinyl alcohol, andcarboxylic acid groups—although it is commonly referred to as acopolymer.

[0005] It is known in the art that many PVOH copolymers, because oftheir structure, can be much more rapidly soluble in cold water than thepartially hydrolyzed type of PVOH homopolymers. Such copolymers havetherefore found considerable utility in the fabrication of packagingfilms for the unit dose presentation of various liquid and powderedproducts including agrochemicals, household and industrial cleaningchemicals, laundry detergents, water treatment chemicals, and the like.

[0006] The manufacture of packaging films for liquid products poses aunique concern, as they must be free of bubbles and pin holes, andcapable of resisting problems such as physical incompatibilityexemplified by “weeping”—a condition whereby the package contents seepfrom the film over a prolonged storage period—caused by certaincomponents typically used in liquid detergent products. The increasedlevel of quality required to manufacture a film and package such liquidsadds significantly to the packaged product cost.

[0007] Conversely, powdered products are far more forgiving when itcomes to packaging. Pin holes and micro bubbles in the film do notpresent problems for packaging powdered products. Physical compatibilityis less problematic, due in part to the non-existence of migratingmaterials in powdered detergents. Weeping does not commonly occur withthe packaging of powdered products. For these reasons the type andquality of PVOH film used to package powered products can besignificantly varied from that for the liquid counterparts.

[0008] However, those in the powdered product industry have beendirected toward the use of either the higher quality, more expensivePVOH copolymer films designed for liquid product packaging or inferiorfilms such as less diverse and more slowly soluble homopolymer-basedfilms including films produced by blown extrusion.

[0009] The present invention has solved this problem of film qualityversus manufacturing cost as it relates to packaging of powderedproduct, as well as other problems faced by those in the industry. Bymaking a less expensive PVOH copolymer film having good water-solublequalities, those in the industry have an alternative source forpackaging powdered products.

SUMMARY

[0010] A water-soluble film suitable for packaging a non-liquid product,including the method for preparing the film composition and packagingfor the non-liquid product, is disclosed. In one particular embodimentof the invention, the film combination comprises a hydrolyzed copolymerof vinyl acetate and methyl acrylate in the range of from about 30 toabout 95 percent by weight, modified starch in the range of from about 4to about 30 percent by weight, plasticizer in the range of from about 5to about 30 percent by weight, lubricant/release agent in the range offrom about 0.0 to about 1.5 percent by weight, and surfactant in therange of from about 0.01 to about 1.5 percent by weight.

[0011] In a preferred embodiment of the invention, the film compositionutilizes a bleaching agent to prevent color drift, such as browning, ofa polymer solution used to cast the film. Oxidizing bleaching agents(e.g., chlorine, chlorinated compounds, oxygen, and oxygenatedcompounds) and reducing bleaching agents (e.g., hydrosulfites,borohydrides, and metabisulfites) are preferred. Examples include sodiumpercarbonate, sodium persulfate, peracetic acid, sodium hydrosulfite andsodium metabisulfite. Sodium percarbonate and sodium metabisulfite arepreferred, and sodium metabisulfite is most preferred.

[0012] Preferably the agent comprises sodium metabisulflte in an amountin the range of from about 0.12 to about 1.0 percent by weight. Mostpreferably, the sodium metabisulfite is used in an amount in the rangeof from about 0.4 to about 0.7 percent by weight.

[0013] A preferred method for preparing a water-soluble copolymer filmfor packaging of a non-liquid product is also disclosed and claimed. Themethod comprises the steps of copolymerizing vinyl acetate and methylacrylate to form a copolymer, hydrolyzing the vinyl acetate-methylacrylate copolymer to form a vinyl alcohol-gamma lactone copolymerhaving a 4% solution viscosity in the range of from about 5 to about 50cps at 20° C., slurrying the hydrolyzed polymer with water, addingmodified starch to the copolymer-water slurry in an amount of from about4.0 to about 25.0 percent by weight, heating the hydrolyzed copolymerand starch slurry to form a solution, treating the solution with causticsoda to create a solution of a copolymer having from about 1 to about 12mol percent carboxylate groups, from about 0 to about 11 mol percentgamma lactone units, and from about 88 to about 99 mol percent vinylalcohol units, and then casting the hot copolymer solution on a suitablesurface to create a film having a thickness in the range of from about0.1 to about 5.0 mils (about 0.0025 to about 0.127 mm).

[0014] A package for containing a non-liquid product is also disclosed.A preferred package comprises at least one compartment comprised of awater-soluble film comprising from about 30 to about 95 percent byweight of a hydrolyzed copolymer of vinyl acetate and methyl acrylate,from about 4 to about 30 percent by weight of modified starch filler,from about 5 to about 30 percent by weight of plasticizer, and fromabout 0.01 to about 1.5 percent by weight of a surfactant.

[0015] In one embodiment the package may be used to deliver a unit doseof a non-liquid agent. The preferred unit dose comprises a packagecomprising a water-soluble film comprising from about 40 to about 90percent by weight of a hydrolyzed copolymer of vinyl acetate and methylacrylate, from about 4 to about 30 percent by weight of a modifiedstarch filler, from about 5 to about 30 percent by weight of aplasticizer, and from about 0.01 to about 1.0 percent by weight of asurfactant, and a non-liquid agent contained within the package. Thenon-liquid agent may be a cleanser, a disinfectant, a polish, aconditioner, or the like.

[0016] Further aspects and advantages will be apparent to those ofordinary skill in the art from a review of the following detaileddescription, taken in conjunction with the drawings. While the film,package, and methods are susceptible of embodiments in various forms,the description hereafter includes specific embodiments with theunderstanding that the disclosure is illustrative, and is not intendedto limit the invention to the specific embodiments described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The embodiments described herein can be more readily understoodwith reference to the appended drawing figures where:

[0018]FIG. 1 is a perspective view of a test apparatus used to analyzethe water disintegration and dissolution of film samples;

[0019]FIG. 2 is a perspective view of the test apparatus and test set-upillustrating the procedure for analyzing the water-solubility of filmsamples; and

[0020]FIG. 3 is a top view of the test set-up of FIG. 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0021] While the invention is susceptible of embodiment in manydifferent forms, this disclosure will describe in detail preferredembodiments of the invention with the understanding that the presentdisclosure is to be considered as an exemplification of the principlesof the invention and is not intended to limit the broad aspect of theinvention to the embodiments illustrated.

[0022] Film Composition:

[0023] The present invention includes a water-soluble film for packaginga non-liquid product. The following is a list of terms used throughoutthe application.

[0024] “Non-liquid” shall refer to any product that has as a component aform characteristic of a solid, including but not limited to powder,caked, shaving, solid, gel, slurry, paste, pelletized, and the like.

[0025] “Package” or “packaging” shall refer to any receptacle or methodsuitable for holding or enclosing, to a substantial degree, a quantityof non-liquid product, without regard to size, shape, or the number ofparts used to form the container or carry out the method.

[0026] Further, all ranges set forth herein include all possible subsetsof ranges and any combinations of such subset ranges. Ranges areinclusive of the stated endpoints.

[0027] The film is based on an amount of a hydrolyzed copolymer of vinylacetate and methyl acrylate and is a vinyl alcohol-gamma lactonecopolymer, in the range of from about 30 to about 95 percent by weight.Preferably, the amount of copolymer is in the range of from about 50 toabout 85 percent by weight. The copolymer may be prepared in any mannerknown by those skilled in the art. A particularly suitable copolymer issold by E. I. duPont de Nemours under the tradename ELVANOL. The ELVANOLrange of water-soluble synthetic polymers has excellent film-forming,emulsifying, and adhesive properties. Such polymers offer resistance tooil, grease and solvents, plus high tensile strength, flexibility, andhigh oxygen barrier.

[0028] Alternatively, and less preferably, a vinyl acetate-methylacrylate copolymer must first undergo hydrolysis (also calledalcoholysis) to form a vinyl alcohol-gamma lactone copolymer. The vinylalcohol-gamma lactone copolymer preferably has a 4% solution viscosityin the range of from about 5 to about 50 cps (0.005 to 0.050 pascalseconds) at 20° C. (68° F.). More preferably the vinyl alcohol-gammalactone copolymer has a 4% solution viscosity in the range of from about8 to about 35 cps (0.008 to 0.035 pascal seconds) and, most preferably,the vinyl alcohol-gamma lactone copolymer has a 4% solution viscosity inthe range of from about 15 to about 25 cps (0.015 to 0.025 pascalseconds).

[0029] The hydrolyzed copolymer initially comprises an amount of gammalactone units preferably from about 2 to about 12 mol percent, morepreferably from about 4 to about 6 mol percent. Modified starch is addedto the hydrolyzed copolymer, which preferably is first slurried withwater, in an amount in the range of from about 4 to about 30 percent byweight, preferably about 4 to about 12 percent by weight. While othermodified starches may be suitable, the preferred modified starch ishydroxyethyl modified starch in an amount of about 10 percent by weight.In another embodiment, the amount of starch is at least 5 percent byweight.

[0030] The composition also comprises plasticizer, such as in the rangeof from about 5 to about 30 percent by weight, preferably about 10 toabout 20 percent by weight, or preferably in the range of from about 20to about 30 percent by weight when sorbitol is present as a plasticizer.

[0031] The composition also preferably comprises lubricant/release agentin the range of from about 0.0 to about 1.5 percent by weight, andsurfactant in the range of from about 0.01 to about 1.5 percent byweight. Other suitable components, such as additional plasticizers,lubricants, and release agents, fillers, extenders, antiblocking agents,detackifying agents, antifoams and other functional ingredients, may beadded in proper amounts to achieve a desired effect to the extent suchcomponents do not inhibit other desired characteristics of the copolymerfilm.

[0032] The copolymer solution preferably is treated with caustic soda(sodium hydroxide), to yield a copolymer solution having from about 1 toabout 12 mol percent, preferably from about 2 to about 6 mol percent,and most preferably from about 3 to about 4 mol percent carboxylategroups, from 0 to about 11 mol percent, preferably from 0 to about 5 molpercent, and most preferably from about 1 to about 2 mol percent gammalactone units, and from about 88 to 99 mol percent, preferably fromabout 92 to about 98 mol percent, and most preferably from about 94 toabout 96 mol percent vinyl alcohol units.

[0033] The copolymer solution is then cast to create a film having athickness in the range of from about 0.5 mils to about 5.0 mils (about0.013 to about 0.127 mm). The film thickness can have a direct effect onthe speed at which the final product will dissolve in water, with thinfilms (e.g., less than 3.0 mil or 0.076 mm) completely dissolving inless time. Conversely, thinner films typically provide less structuralprotection than their thicker film counterparts. A balance must bestruck between these and other factors. For many applications, apreferable film thickness is in the range of from about 0.5 to about 3.0mils (about 0.013 to about 0.076 mm), and most preferably in the rangeof from about 1.0 to about 2.0 mils (about 0.025 to about 0.050 mm).

[0034] During preparation of the copolymer solution a browning effectcan occur. It is desirable in most applications that the water-solublefilm have a clear and colorless appearance. To combat this, and anyother known color drift to which the copolymer solution may besusceptible, a suitable bleaching agent can be added to the copolymersolution. The use of sodium metabisulfite has been found tosubstantially maintain the solution clarity and colorlessness duringpreparation when used in an amount in the range of from about 0.12 toabout 1.0 percent by weight, most preferably in an amount from about 0.4to about 0.7 percent by weight.

[0035] Suitable plasticizers include, but are not limited to, glycerin,diglycerin, sorbitol, ethylene glycol, diethylene glycol, triethyleneglycol, tetraethylene glycol, propylene glycol, polyethylene glycols upto 400 MW, neopentyl glycol, trimethylolpropane, polyether polyols andethanolamines. Preferred plasticizers are glycerin, triethyleneglycol,propylene glycol and trimethylolpropane.

[0036] Suitable surfactants may include the nonionic, cationic, anionicand zwitterionic classes. Preferably, the surfactants will be of thenonionic, cationic or zwitterionic classes or combinations of these.Suitable surfactants include, but are not limited to, polyoxyethylenatedpolyoxypropylene glycols, alcohol ethoxylates, alkylphenol ethoxylates,tertiary acetylenic glycols and alkanolamides (nonionics),polyoxyethylenated amines, quaternary ammonium salts and quaternizedpolyoxyethylenated amines (cationics), and amine oxides, N-alkylbetainesand sulfobetaines (zwitterionics). Preferred surfactants are alcoholethoxylates, quaternary ammonium salts and amine oxides.

[0037] Suitable lubricants/release agents include, but are not limitedto, fatty acids and their salts, fatty alcohols, fatty esters, fattyamines, fatty amine acetates and fatty amides. Preferredlubricants/release agents are fatty acids, fatty acid salts, and fattyamine acetates.

[0038] Suitable fillers/extenders/antiblocking agents/detackifyingagents include, but are not limited to, starches, modified starches,crosslinked polyvinylpyrrolidone, crosslinked cellulose,microcrystalline cellulose, silica, metallic oxides, calcium carbonate,talc and mica. Preferred materials are starches, modified starches andsilica. If used, the preferred amount of suchfiller/extender/antiblocking agent/detackifying agent in thewater-soluble film of the present invention is between 0.1% and 25% byweight, more preferably between 1% and 15% by weight, and preferablybetween 1% and 5% by weight if starch is absent.

[0039] Suitable antifoams include, but are not limited to, those basedon polydimethylsiloxanes and hydrocarbon blends. If used, the preferredamount of antifoam in the water-soluble film of the present invention isbetween 0.001% and 0.5%, more preferably between 0.01% and 0.1% byweight.

[0040] Film Formation:

[0041] The preferred method for preparing the water-soluble copolymerfilm comprises the steps of copolymerizing vinyl acetate and methylacrylate to form a copolymer. Alternatively, this vinyl acetate-methylacrylate copolymer may be more readily purchased. In either case, thenext steps include hydrolyzing the vinyl acetate-methyl acrylatecopolymer to form a vinyl alcohol-gamma lactone copolymer having a 4%solution viscosity in the range of from about 5 to about 50 cps at 20°C., and slurrying the hydrolyzed polymer with water while addingmodified starch to the copolymer-water slurry in an amount of from about4.0 to about 25.0 percent by weight. Preferably the amount of modifiedstarch is about 4 to about 12 percent by weight. The hydrolyzedcopolymer and starch slurry is then heated to boiling point to form asolution.

[0042] The solution is then treated with caustic soda to create asolution of a copolymer having from about 1 to about 12 mol percentcarboxylate groups, from about 0 to about 11 mol percent gamma lactoneunits, and from about 88 to about 99 mol percent vinyl alcohol units.More preferable ranges have been previously stated. The next step ismaintaining the solution at a temperature in the range of from about160° F. to about 200° F. (about 71° C. to about 93° C.), and thencasting the hot copolymer solution on a suitable surface to create afilm having a thickness in the range of from about 0.1 to about 5.0 mils(about 0.0025 to about 0.127 mm).

[0043] The treated solution can undergo browning while being held athigh temperatures. This is undesirable for most applications, wherein aclear film is sought. Therefore, the method can further comprise thestep of adding a bleaching agent, such as sodium metabisulfite, in anamount greater than 0.12 percent by weight to substantially reduce orprevent browning of the heated solution. Most preferably, a bisulfite isadded in the amount of from about 0.4 to about 0.7 percent by weight.

[0044] The resulting film can then be formed into a package forcontaining a non-liquid product, as previously described. Steps forforming a suitable package are known by those skilled in the art forsimilar handling films, or can be derived without undue experimentation.A preferred requirement of the film, and therefore the formed package,is that it be capable of complete dissolution in water in a relativelyshort period of time. A preferred film of the present invention, at athickness of about 1.5 mil (about 0.038 mm), dissolves in water at atemperature of about 20° C. in less than 60 seconds.

[0045] The following test procedure, referred to herein as MonoSol TestMethod 205 (MSTM 205), is used to determine the time required for awater-soluble film to break apart (disintegrate) and its subsequentrelative dissolution time when held stationary. The test procedure isdisclosed with reference to drawing FIGS. 1-3.

MonoSol Test Method 205 (MSTM 205)

[0046] Apparatus and Materials.

[0047] 600 mL Beaker 12

[0048] Magnetic Stirrer 14 (Labline Model No. 1250 or equivalent)

[0049] Magnetic Stirring Rod 16 (5 cm)

[0050] Thermometer (0 to 100° C., ±1° C.)

[0051] Template, Stainless Steel (3.8 cm×3.2 cm)

[0052] Timer, (0-300 seconds, accurate to the nearest second)

[0053] Polaroid 35 mm Slide Mount 20 (or equivalent)

[0054] MonoSol 35 mm Slide Mount Holder 25 (or equivalent, see FIG. 1)

[0055] Distilled Water

[0056] Test Specimen:

[0057] 1. Cut three test specimens from film sample using stainlesssteel template (i.e., 3.8 cm×3.2 cm specimen). If cut from a film web,specimens should be cut from areas of web evenly spaced along thetransverse direction of the web.

[0058] 2. Lock each specimen in a separate 35 mm slide mount 20.

[0059] 3. Fill beaker 12 with 500 mL of distilled water. Measure watertemperature with thermometer and, if necessary, heat or cool water tomaintain temperature at 20° C. (about 68° F.).

[0060] 4. Mark height of column of water. Place magnetic stirrer 14 onbase 27 of holder 25. Place beaker 12 on magnetic stirrer 14, addmagnetic stifling rod 16 to beaker 12, turn on stirrer 14, and adjuststir speed until a vortex develops which is approximately one-fifth theheight of the water column. Mark depth of vortex.

[0061] 5. Secure the 35 mm slide mount 20 in the alligator clamp 26 ofthe MonoSol 35 mm slide mount holder 25 (FIG. 1) such that the long end21 of the slide mount 20 is parallel to the water surface, asillustrated in FIG. 2. The depth adjuster 28 of the holder 25 should beset so that when dropped, the end of the clamp 26 will be 0.6 cm belowthe surface of the water. One of the short sides 23 of the slide mount20 should be next to the side of the beaker 12 with the other positioneddirectly over the center of the stirring rod 16 such that the filmsurface is perpendicular to the flow of the water, as illustrated inFIG. 3.

[0062] 6. In one motion, drop the secured slide and clamp into the waterand start the timer. Disintegration occurs when the film breaks apart.When all visible film is released from the slide mount, raise the slideout of the water while continuing to monitor the solution forundissolved film fragments. Dissolution occurs when all film fragmentsare no longer visible and the solution becomes clear.

[0063] Data Recording:

[0064] The results should include the following:

[0065] complete sample identification;

[0066] individual and average disintegration and dissolution times; and

[0067] water temperature at which the samples were tested.

[0068] Standard quality control procedures may be followed forwater-soluble PVOH film, with respect to bubble and pin-hole inspection,however, such quality checks are not absolutely necessary given thesolid state of the contained product. A unit dose of a non-liquid agentcontained within the formed package does not necessarily pose the samepackaging problems as a liquid product. With respect to the use of sucha unit dose, however, no procedural changes are required. That is,merely adding the unit dose package to the appropriate quantity of waterand following the necessary stirring or agitation times yields thedesired cleaning, conditioning, or disinfectant solution.

[0069] While specific embodiments have been illustrated and described,numerous modifications are possible without departing from the spirit ofthe invention.

We claim:
 1. A water-soluble film for packaging a non-liquid product,the film comprising: a hydrolyzed copolymer of vinyl acetate and methylacrylate in a range of from about 30 to about 95 percent by weight;modified starch in a range of from about 4 to about 30 percent byweight; plasticizer in a range of from about 5 to about 30 percent byweight; lubricant/release agent in a range of from about 0.0 to about1.5 percent by weight; and surfactant in a range of from about 0.01 toabout 1.5 percent by weight.
 2. The composition of claim 1, wherein themodified starch comprises hydroxyethyl modified starch.
 3. Thecomposition of claim 2, wherein the amount of modified starch is about 4to about 12 percent by weight.
 4. The composition of claim 1, whereinthe water-soluble film, at a thickness of about 1.5 mil (about 0.038mm), dissolves in less than 60 seconds in water at a temperature ofabout 20° C. (about 68° F.) in accordance with MonoSol Test Method MSTM205.
 5. The composition of claim 1, wherein the hydrolyzed copolymer hasa 4% solution viscosity in a range of about 5 to about 50 cps (about0.005 to about 0.050 pascal seconds) at 20° C. (about 68° F.).
 6. Thecomposition of claim 5, wherein the hydrolyzed copolymer has a 4%solution viscosity in a range of about 8 to about 35 cps (about 0.008 toabout 0.035 pascal seconds) at 20° C. (about 68° F.).
 7. The compositionof claim 6, wherein the hydrolyzed copolymer has a 4% solution viscosityin a range of about 15 to about 25 cps (about 0.015 to about 0.025pascal seconds) at 20° C. (about 68° F.).
 8. The composition of claim 1,wherein the copolymer film thickness is in a range of from about 0.1 toabout 5.0 mils (about 0.0025 to about 0.127 mm).
 9. The composition ofclaim 8, wherein the copolymer film thickness is in a range of fromabout 0.5 to about 3.0 mils (about 0.013 to about 0.076 mm).
 10. Thecomposition of claim 9, wherein the copolymer film thickness is in arange of from about 1.0 to about 2.0 mils (about 0.025 to about 0.050mm).
 11. The composition of claim 1, wherein the amount of plasticizeris in a range of from about 20 to about 30 percent by weight.
 12. Thecomposition of claim 1, further comprising a bleaching agent forcontrolling color drift in the film.
 13. The composition of claim 12,wherein the bleaching agent is sodium metabisulfite.
 14. The compositionof claim 13, wherein the amount of sodium metabisulfite is in a range offrom about 0.12 to about 1.0 percent by weight.
 15. The composition ofclaim 14, wherein the amount of sodium metabisulfite is in a range offrom about 0.4 to about 0.7 percent by weight.
 16. The composition ofclaim 1, wherein the hydrolyzed copolymer initially comprises an amountof from about 1 to about 12 mol percent gamma lactone units, and whereinafter treatment with a caustic soda the hydrolyzed copolymer comprisesfrom about 1 to about 12 mol percent carboxylate groups and from about 0to about 11 mol percent gamma lactone units.
 17. The composition ofclaim 1, wherein the hydrolyzed copolymer initially comprises an amountof from about 2 to about 8 mol percent gamma lactone units, and whereinafter treatment with a caustic soda the hydrolyzed copolymer comprisesfrom about 2 to about 6 mol percent carboxylate groups and from about 0to about 5 mol percent gamma lactone units.
 18. The composition of claim1, wherein the hydrolyzed copolymer initially comprises an amount offrom about 4 to about 6 mol percent gamma lactone units, and whereinafter treatment with a caustic soda the hydrolyzed copolymer comprisesfrom about 3 to about 4 mol percent carboxylate groups and from about 1to about 2 mol percent gamma lactone units.
 19. A package for containinga non-liquid product, the package comprising at least one compartmentcomprised of a water-soluble film according to claim
 1. 20. The packageof claim 19, wherein the amount of modified starch is about 4 to about12 percent by weight.
 21. A unit dose of a non-liquid agent comprising:a package according to claim 19, and a non-liquid agent contained withinthe package.
 22. The unit dose of claim 21, wherein the amount ofmodified starch is about 4 to about 12 percent by weight.
 23. A methodfor preparing a water-soluble copolymer film for packaging of anon-liquid product, the method comprising the steps of: copolymerizingvinyl acetate and methyl acrylate to form a copolymer; hydrolyzing thevinyl acetate-methyl acrylate copolymer to form a vinyl alcohol-gammalactone copolymer having a 4% solution viscosity in a range of fromabout 5 to about 50 cps at 20° C.; slurrying the hydrolyzed polymer withwater; adding modified starch to the copolymer-water slurry in an amountof from about 4.0 to about 25.0 percent by weight; heating thehydrolyzed copolymer and starch slurry to form a solution; treating thesolution with caustic soda to create a solution of a copolymer havingfrom about 1 to about 12 mol percent carboxylate groups, from about 0 toabout 11 mol percent gamma lactone units, and from about 88 to about 99mol percent vinyl alcohol units; and casting the hot copolymer solutionon a suitable surface to create a film having a thickness in a range offrom about 0.1 to about 5.0 mils (about 0.0025 to about 0.127 mm). 24.The method of claim 23, further comprising the step of adding sodiummetabisulfite in an amount greater than 0.12 percent by weight toprevent browning of the heated solution.
 25. The method of claim 24,wherein the amount of sodium metabisulfite is in a range of from about0.4 to about 0.7 percent by weight.
 26. The method of claim 23, whereinthe copolymer solution comprises from about 2 to about 6 mol percentcarboxylate groups, from about 0 to about 5 mol percent gamma lactoneunits, and from about 92 to about 98 mol percent vinyl alcohol units.27. The method of claim 23, wherein the copolymer solution comprisesfrom about 3 to about 4 mol percent carboxylate groups, from about 1 toabout 2 mol percent gamma lactone units, and from about 94 to about 96mol percent vinyl alcohol units.
 28. The method of claim 23, wherein theamount of modified starch used is about 4 to about 12 percent by weight.29. The method of claim 28, wherein the modified starch compriseshydroxyethyl modified starch.
 30. The method of claim 23, furthercomprising the step of forming the resulting film into a package forpackaging a non-liquid product.
 31. The method of claim 28, wherein thewater-soluble film at a thickness of about 1.5 mil (about 0.038 mm)dissolves in water at a temperature of about 20° C. (about 68° F.) inless than 60 seconds in accordance with MonoSol test method MSTM 205.32. The method of claim 23, wherein the water-soluble film at athickness of about 1.5 mil (about 0.038 mm) dissolves in water at atemperature of about 20° C. (about 68° F.) in less than 60 seconds inaccordance with MonoSol test method MSTM
 205. 33. A method for preparinga water-soluble copolymer film for packaging of a non-liquid product,the method comprising the steps of: providing a vinyl acetate-methylacrylate copolymer; hydrolyzing the vinyl acetate-methyl acrylatecopolymer to form a vinyl alcohol-gamma lactone copolymer having a 4%solution viscosity in a range of from about 5 to about 50 cps at 20° C.;slurrying the hydrolyzed polymer with water; adding modified starch tothe copolymer-water slurry in an amount of from about 4 to about 25.0percent by weight; heating the vinyl alcohol-gamma lactone copolymer andstarch to form a solution; treating the solution with caustic soda tocreate a solution of a copolymer having from about 1 to about 12 molpercent carboxylate groups, from about 0 to about 11 mol percent gammalactone units, and from about 88 to 99 mol percent vinyl alcohol units;casting the hot copolymer solution on a suitable surface to create afilm having a thickness in a range of from about 0.1 to about 5.0 mils(about 0.0025 to about 0.127 mm).